The present invention relates generally to the production of diapers, particularly disposable diapers, and more specifically, to methods of producing such diapers.
Over recent decades, disposable diapers have come to dominate the market for both infant diaper products and adult incontinence products, largely replacing traditional cloth fabric diapers and incontinent garments. Such disposable diapers, both for infants and adults, basically comprise three main components: an inner web or sheet of a liquid permeable material, typically a non-woven, for direct contact with the wearer's body, an intermediate core of a liquid absorbent material typically in the form of a pad of hydrophilic fibers and often including a supplementary absorbent medium such as a super absorbent polymeric material for capturing and holding bodily fluids passing through the permeable inner layer, and an outer web or sheet of a liquid impervious material usually comprised of a laminate of film and non-woven materials to retain liquid within the absorbent core against leakage from the diaper.
For optimal fitting of such diapers to the typical contours of a wearer's body, such diapers commonly are formed of an overall hourglass shape providing a narrowed crotch area situated between wider front and back portions respectfully for covering the abdomen and buttocks of a wearer. The laterally extending margins of the wider front and back portions of the diaper form wing-like tabs which can be overlapped with one another when worn so as to encircle fully the waist of the wearer and, together with the crotch portion, to form leg openings encircling the upper legs of the wearer adjacent the wearer's crotch. The wing-like tab portions are typically provided with fastener elements, such as adhesive elements, hook-and-loop fastener elements, or other appropriate means for securely holding the tab-portions in overlapping relationship. The diapers are also often provided with elastic bands or filaments within the lateral borders of the crotch portion to enhance conformance of the crotch portion to the body of the wearer and thereby additionally mitigate risk of fluid leakage.
The process of making diapers of the basic above-described construction is generally well known in the relevant art and is accomplished by a substantially fully automated process wherein respective webs of liquid impervious and liquid permeable sheet roll stock are fed simultaneously with a web of absorbent padding material through so-called converting machinery which orients the respective webs in a sandwich-like relationship to be assembled by an appropriate manner of bonding of the webs, e.g., by ultrasonic welding. Each respective web is typically of an elongate continuously length of material having parallel lateral side edges. In the process of feeding the web of the outer liquid impervious layer, appropriate segments of the material are severed from each opposite side of the moving sheet roll stock at regular intervals to form a repeating pattern of hourglass shapes along the length of the advancing web material. In some cases, the sheet roll stock of liquid permeable material for forming the inner web may be of a dimension laterally coextensive with that of the outer web of material, in which case corresponding segments of material are severed from the inner web also, but alternatively the inner web may be of a more narrow lateral dimension to only overlie the crotch portion and the corresponding central regions of the front and rear portions of the outer web.
Disadvantageously, all such materials severed from the outer web, and optionally also from the inner web, constitute waste which must be discarded and may comprise up to approximately 11 percent of the overall costs of materials utilized in diapers. Accordingly, there is a substantial recognized need within the industry for alternative methodologies or techniques in the fabrication of such diapers that will enable the creation of discarded waste material to be eliminated or at least significantly reduced.